Can't get contour plots to form/incompatible grids & trouble creating scripts

[Mark Schuster]

Hello all

I am new to GRADS, and I am working with files that I downloaded from the
NCEP reanalysis page that are in .nc format.  If I type something like...

sdfopen shum9495.nc
set lat 60
set lon 250
set t 1
d vint(1000.,shum,350)

I will get the vertically integrated water content at that point which is
great, but I am more interested in the spatial distribution (contour plot),
so I make the lat and lon vary.  So if I type

sdfopen shum9495.nc
set lat 50 70
set lon 230 250
set t 1
d vint(1000.,shum,350)

I get an error about incompatible grids, and I get the error box "this
program has performed an illegal operation and will be shut down".  I have
no idea why I don't get a contour plot, as the data I downloaded is within
the grid that I specify.  I am sure that it is probably a very simple thing
that I am totally unaware of that I am doing wrong since I am new to grads.

Also, for creating scripts, do I just type it up in notepad, and type run
script in the grads window?  Extension is suppose to be .gs, but if you
type it in notepad, it has a .txt extension.

Many thanks!

Mark